Mixed Race Studies

New gene variants reveal the evolution of human skin color

Science
2017-11-12

Ann Gibbons, Contributing Correspondent

Researchers have identified genes that help create diverse skin tones, such as those seen in the Agaw (left) and Surma (right) peoples of Africa. ALESSIA RANCIARO & DR. SIMON R. THOMPSON

Most people associate Africans with dark skin. But different groups of people in Africa have almost every skin color on the planet, from deepest black in the Dinka of South Sudan to beige in the San of South Africa. Now, researchers have discovered a handful of new gene variants responsible for this palette of tones.

The study, published online this week in Science, traces the evolution of these genes and how they traveled around the world. While the dark skin of some Pacific Islanders can be traced to Africa, gene variants from Eurasia also seem to have made their way back to Africa. And surprisingly, some of the mutations responsible for lighter skin in Europeans turn out to have an ancient African origin.

“This is really a landmark study of skin color diversity,” says geneticist Greg Barsh of the HudsonAlpha Institute for Biotechnology in Huntsville, Alabama.

Researchers agree that our early australopithecine ancestors in Africa probably had light skin beneath hairy pelts. “If you shave a chimpanzee, its skin is light,” says evolutionary geneticist Sarah Tishkoff of the University of Pennsylvania, the lead author of the new study. “If you have body hair, you don’t need dark skin to protect you from ultraviolet [UV] radiation.”

Until recently, researchers assumed that after human ancestors shed most body hair, sometime before 2 million years ago, they quickly evolved dark skin for protection from skin cancer and other harmful effects of UV radiation. Then, when humans migrated out of Africa and headed to the far north, they evolved lighter skin as an adaptation to limited sunlight. (Pale skin synthesizes more vitamin D when light is scarce.)…

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Race has a hold on history, but it no longer has a place in science. The sheer instability and potential for misinterpretation render race useless as a scientific concept. Inventing new vocabularies of human diversity and inequity won’t be easy, but is necessary.

Nina Jablonski, “2014 : What Scientific Idea is Ready for Retirement?,” Edge, January 16, 2014. http://www.edge.org/responses/what-scientific-idea-is-ready-for-retirement.

Annual Question (2014): What Scientific Idea is Ready for Retirement? [Race]

Edge
2014-01-16

Race

Nina Jablonski, Biological Anthropologist and Paleobiologist; Distinguished Professor of Anthropology
Pennsylvania State University

Race has always been a vague and slippery concept. In the mid-eighteenth century, European naturalists such as Linnaeus, Comte de Buffon, and Johannes Blumenbach described geographic groupings of humans who differed in appearance. The philosophers David Hume and Immanuel Kant both were fascinated by human physical diversity. In their opinions, extremes of heat, cold, or sunlight extinguished human potential. Writing in 1748, Hume contended that, “there was never a civilized nation of any complexion other than white.”

Kant felt similarly. He was preoccupied with questions of human diversity throughout his career, and wrote at length on the subject in a series of essays beginning in 1775. Kant was the first to name and define the geographic groupings of humans as races (in German, Rassen). Kant’s races were characterized by physical distinctions of skin color, hair form, cranial shape, and other anatomical features and by their capacity for morality, self-improvement, and civilization. Kant’s four races were arranged hierarchically, with only the European race, in his estimation, being capable of self-improvement…

…The mid-twentieth century witnessed the continued proliferation of scientific treatises on race. By the 1960s, however, two factors contributed to the demise of the concept of biological races. One of these was the increased rate of study of the physical and genetic diversity human groups all over the world by large numbers of scientists. The second factor was the increasing influence of the civil rights movement in the United States and elsewhere. Before long, influential scientists denounced studies of race and races because races themselves could not be scientifically defined. Where scientists looked for sharp boundaries between groups, none could be found…

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